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#pragma once

#include <pcl/registration/transformation_estimation.h>
#include <pcl/registration/warp_point_rigid.h>
#include <pcl/cloud_iterator.h>

namespace pcl
{
  namespace registration
  {
    /** \brief @b TransformationEstimationSymmetricPointToPlaneLLS implements a Linear Least Squares (LLS) approximation
      * for minimizing the symmetric point-to-plane distance between two clouds of corresponding points with normals.
      *
      * For additional details, see
      *   "Linear Least-Squares Optimization for Point-to-Plane ICP Surface Registration", Kok-Lim Low, 2004
      *   "A Symmetric Objective Function for ICP", Szymon Rusinkiewicz, 2019
      *
      * \note The class is templated on the source and target point types as well as on the output scalar of the
      * transformation matrix (i.e., float or double). Default: float.
      * \author Matthew Cong
      * \ingroup registration
      */
    template <typename PointSource, typename PointTarget, typename Scalar = float>
    class TransformationEstimationSymmetricPointToPlaneLLS : public TransformationEstimation<PointSource, PointTarget, Scalar>
    {
      public:
        using Ptr = shared_ptr<TransformationEstimationSymmetricPointToPlaneLLS<PointSource, PointTarget, Scalar> >;
        using ConstPtr = shared_ptr<const TransformationEstimationSymmetricPointToPlaneLLS<PointSource, PointTarget, Scalar> >;

        using Matrix4 = typename TransformationEstimation<PointSource, PointTarget, Scalar>::Matrix4;
        using Vector6 = Eigen::Matrix<Scalar, 6, 1>;

        TransformationEstimationSymmetricPointToPlaneLLS () : enforce_same_direction_normals_ (true) {};
        ~TransformationEstimationSymmetricPointToPlaneLLS () {};

        /** \brief Estimate a rigid rotation transformation between a source and a target point cloud using SVD.
          * \param[in] cloud_src the source point cloud dataset
          * \param[in] cloud_tgt the target point cloud dataset
          * \param[out] transformation_matrix the resultant transformation matrix
          */
        inline void
        estimateRigidTransformation (
            const pcl::PointCloud<PointSource> &cloud_src,
            const pcl::PointCloud<PointTarget> &cloud_tgt,
            Matrix4 &transformation_matrix) const override;

        /** \brief Estimate a rigid rotation transformation between a source and a target point cloud using SVD.
          * \param[in] cloud_src the source point cloud dataset
          * \param[in] indices_src the vector of indices describing the points of interest in \a cloud_src
          * \param[in] cloud_tgt the target point cloud dataset
          * \param[out] transformation_matrix the resultant transformation matrix
          */
        inline void
        estimateRigidTransformation (
            const pcl::PointCloud<PointSource> &cloud_src,
            const std::vector<int> &indices_src,
            const pcl::PointCloud<PointTarget> &cloud_tgt,
            Matrix4 &transformation_matrix) const override;

        /** \brief Estimate a rigid rotation transformation between a source and a target point cloud using SVD.
          * \param[in] cloud_src the source point cloud dataset
          * \param[in] indices_src the vector of indices describing the points of interest in \a cloud_src
          * \param[in] cloud_tgt the target point cloud dataset
          * \param[in] indices_tgt the vector of indices describing the correspondences of the interest points from \a indices_src
          * \param[out] transformation_matrix the resultant transformation matrix
          */
        inline void
        estimateRigidTransformation (
            const pcl::PointCloud<PointSource> &cloud_src,
            const std::vector<int> &indices_src,
            const pcl::PointCloud<PointTarget> &cloud_tgt,
            const std::vector<int> &indices_tgt,
            Matrix4 &transformation_matrix) const override;

        /** \brief Estimate a rigid rotation transformation between a source and a target point cloud using SVD.
          * \param[in] cloud_src the source point cloud dataset
          * \param[in] cloud_tgt the target point cloud dataset
          * \param[in] correspondences the vector of correspondences between source and target point cloud
          * \param[out] transformation_matrix the resultant transformation matrix
          */
        inline void
        estimateRigidTransformation (
            const pcl::PointCloud<PointSource> &cloud_src,
            const pcl::PointCloud<PointTarget> &cloud_tgt,
            const pcl::Correspondences &correspondences,
            Matrix4 &transformation_matrix) const override;

        /** \brief Set whether or not to negate source or target normals on a per-point basis such that they point in the same direction.
        * \param[in] enforce_same_direction_normals whether to negate source or target normals on a per-point basis such that they point in the same direction.
        */
        inline void
        setEnforceSameDirectionNormals (bool enforce_same_direction_normals);

        /** \brief Obtain whether source or target normals are negated on a per-point basis such that they point in the same direction or not */
        inline bool
        getEnforceSameDirectionNormals ();

      protected:

        /** \brief Estimate a rigid rotation transformation between a source and a target
          * \param[in] source_it an iterator over the source point cloud dataset
          * \param[in] target_it an iterator over the target point cloud dataset
          * \param[out] transformation_matrix the resultant transformation matrix
          */
        void
        estimateRigidTransformation (ConstCloudIterator<PointSource>& source_it,
                                     ConstCloudIterator<PointTarget>& target_it,
                                     Matrix4 &transformation_matrix) const;

        /** \brief Construct a 4 by 4 transformation matrix from the provided rotation and translation.
          * \param[in] parameters (alpha, beta, gamma, tx, ty, tz) specifying rotation about the x, y, and z-axis and translation along the the x, y, and z-axis respectively
          * \param[out] transformation_matrix the resultant transformation matrix
          */
        inline void
        constructTransformationMatrix (const Vector6 &parameters,
                                       Matrix4 &transformation_matrix) const;

      /** \brief Whether or not to negate source and/or target normals such that they point in the same direction */
        bool enforce_same_direction_normals_;

    };
  }
}

#include <pcl/registration/impl/transformation_estimation_symmetric_point_to_plane_lls.hpp>
